GA engines On Condition

[nomorecatering]

Was talking to a bloke last week who owns an Archer. He said his engine was just on the 2000 hrs recomended TBO time and was wondering if he should have it overhauled now or keep it running on condition. A few salient points>

It was a factory newie when it was installed by him, straight out of the box.

Its carefully flown for private use, mosty on 2 to 4 hr legs.

Aircrafts 100 hrlys are done at one of the better shops around. has an oil analysis done each time and no signs of metal in the oil so far.

He will get new cylinders when an overhaul is done, can anyone recomend superior, ECI or factory Lycomming.

Lastly, if the engine is running fine, how long could he go for before finally doing the overhaul. Has anyone had experiance with past TBO ops.

[THE IRON MAIDEN]

I'd say when the engine stops by itself it might be a good time to get a new one.

:} :} :} :eek:

[Chimbu chuckles]

Print this article off and give it to him.

http://www.avweb.com/news/savvyaviator/savvy_aviator_45_how_risky_is_going_past_tbo_195241-1.html

[Cyclone Bob]

Good old CAA in EnZed are in the process of banning 'on condition'. I have no idea why. I know of a few people whose engines are running out of calendar time who aren't too happy!
I wouldn't be surprised if the engine in the aforementioned Archer went to 3000hrs. I've seen plenty of lycoming 4 bangers exceed this total with no problems. Every hour you get past TBO is a bonus and almost like money in the bank! If it were my motor, I'd not hesitate to run it on condition as there is no evidence to suggest that doing so compromises safety. The Avweb article mentioned by CC is on the money!

[kiwiblue]

Where I worked in NZ we routinely ran our engines "on-condition" in commercial ops. That approval gave us a 10% engine-life extension -extremely valuable at any time, but particularly so during the peak season. On one memorable occasion, one of my engines (an O-540) which had reached TBO+10%, came out of the airframe and was dispatched to the overhaul facility. A few days later the phone went, it being the engineer from the overhaul shop. He wanted to know "why was the engine in his workshop?" I asked him had he checked the engine logbook -he hadn't, so I told him he should, then ring me back. When he did ring back, his words were something like "there's nothing wrong with this engine, stick it back in the airframe and put another 2,200 hrs on it". So yeah I conditionally agree with what has been said so far, and the article linked...

I have also seen an identical engine "babied" by its operator fall over in just 1,200 hours. So my conditional endorsement is based on how the engine is treated throughout its life. However, if an engine gets to 2,000 hours (on-going, appropriate maintenance checks) without major issues, it should manage to go further without a problem!

There was an excellent thread here previously about big-bore mills (http://www.pprune.org/forums/showthread.php?t=272328) that raised many interesting points -and exploded more than a few myths. Worth revisiting I reckon, well relevant to this discussion.

[the wizard of auz]

I managed nearly 5K on a O320D2J in a mustering bus, with one top overhaul at about 2200 and another at 4000. when stripped at 4000, everything was miked and it was all still well within limits. then again, I have seen other engines that didn't make half of TBO before giving up.

[witwiw]

If the engine is deemed mechanically fine by a LAMEy, then there is no reason why you cannot safely run the engine on condition.
Don't have much experience with them, but did fly an aircraft that went for I think another 200 or so hours. Owners and operators must be pleased at the extra use/revenue and delayed overhaul cost...

Of course it depends on previous treatment, some engines dont last the TBO period, some last a little longer and some longer still.

Just when you run it on condition, every subsequent 100hrly could possibly be a bit more thorough.
If the said person has money to burn (we all must be able to in this game :ugh:) then he could spend now and do the overhaul. Its really up to them, but going back to the first sentence, if its checked fine by the appropriate person (be it before or after the TBO) then it should be right for the next 100hrs !

[Syd Chrome]

If the engine is deemed mechanically fine by a LAMEy, then there is no reason why you cannot safely run the engine on condition.
Trouble is with comments like these is that every operator wants to run (say) 2400 hrs out of a (say) 2000 hr Rec TBO engine. It doesn't affect the owners insurance as he's got a nice new fresh maintenance release...but if it should crap itself when past rec TBO and people get injured, then the poor ole LAME who signed it out is exposed. They (prosecution) will not accept CASA ADs in court and will merely use the Lycoming or Continental Rec TBO as the limit for that engine..thats why a lot of LAMEs will not entertain the idea. LAMEs should be able to stand behind CASA ADs as being law and if that causes people to be injured then CASA should be held resposnible not the LAME.
SC

[witwiw]

Interesting, Syd Chrome.
Has that ever been the case? It is food for thought.

[VH-XXX]

I was a little surprised to hear recently that for $180 CASA will give an excemption for an engine to run 'on-condition' indefinitely whilst in the charter category. Good for those that didn't budget for their overhaul as the extra hours you get might cover an overhaul.

[Syd Chrome]

I was a little surprised to hear recently that for $180 CASA will give an excemption for an engine to run 'on-condition' indefinitely whilst in the charter category

XXX, I'd be very surprised if they did that. What might have happenned could be an extension to the calendar requirements for overhaul due to a recent bulk strip or tear down of the engine. Maybe cracked crankcase or prop strike etc. On Condition in Charter is a no-no almost everywhere, however it has been seen many times that different regions of CASA use different rule books so although I doubt it, it may have occured. Would love to know more if you could find out some more ..:confused:

[2599 danny]

one thing to i have found overhauling these engines is some of the private operators that are only doing two three hundred hours a year with a month or more of inactivity having the cam at the top the engine is the oil drains and leaves the camshaft dry and on overhaul I have seen a few camshafts
very badly worn

[kingtoad]

I'd say run it out to 2200 hours if it is going well. Engines "on condition" require the lame to fill out an "Engine Condition report" at every periodic inspection. I'd definitely be getting 50 hrly oil & filter change with filter inspection.

And yes - leaving your engine sit for weeks on end without running will lead to an early o'haul from excessive wear, corrosion etc.

I'd like to hear some professional opinions on the liabillity side of things in a post (fatal) accident senario with an engine "on condition". Syd Chrome does raise some valid Q's.

In my experience - don't touch ECI cylinders. We've replaced about 7 ECIs on a 6 cylinder engine in a C414A we maintain. The cracks appear quite suddenly (ie within 55 hrs of flight time). Mind you it is a TSIO-520-NB which is working much harder than an O-360 (and yes I know the 520 is a TCM and the 360 being discussed is a Lyc). But it certainly has soured my opinion of ECIs (look up the AD's on the ECIs :ok:).

[ForkTailedDrKiller]

My LAME refuses to have anything to do with "On condition".

He is firmly of the belief that the potential liability risk in the event of a failure leading to fatalities is simply NOT acceptable.

Dr

[aldee]

We run our Archer3 out to 2300 hours on its first life o 360,sent it in for a blue seal o/haul with eci cylinders.
Made black oil from day one, lost compression on 1 cyl. @ 300hrs.Turns out theres a random problem with the plasma coated rings in some installs in oz,hone and cast iron rings and alls good.Excellent service from the distributer/overhaul shop, all costs covered.
Bit of a shame, all the data reads good in theory just doesn't seem to be so in practice.Don't know what I'd use next time.
From our lame's point of view,it had been maintained by them from new and they were comfortable with signing it out.

[PA39]

The biggest problems lie with the Insurance Companies. They will frown on anything over 200 TBO. Then the poor old LAME is going to cop it up the backside as soon as there is an accident due to engine failure as he signed it out last. So they will be reluctant to let it go too long.

FWIW If the engine has good compressions, oil consumption is good and the analysis is good, and everything is within parameters, well there is no mechanical reason why it should not be allowed to continue on condition. Of course the components will have to be overhauled as required.

[VH-XXX]

Syd, you are probably right. It did have a bulk-strip due to prop strike a few years back - good call :D

[Syd Chrome]

Insurance coverage is not a problem - nor is it the issue here. We have and I believe any MRO can get insurance to cover OC engines up to a limit of 20% over-run. The issue here is the plight of the LAME that signs it out. He is not covered at all in a court of law and certifies the engine at his own risk. What should happen, is that the LAME is able to stand behind the CASA AD (the last 'A' in CASA stands for Authority [LOL] ) and if its an AD , made by parliament via due process, then its law. Bullet-proof law. In court its not. Prosecution dismisses CASA as an 'authority' and will use the engine manufactuers rec TBO to base their claim. LAME should be protected by the fact that he is complying with law as derived by CASA but he is all alone. The only way to protect yourself as a LAME is IAW the engine manufacturers recommendations. Dont stand behind CASA - it will cost you dearly. Don't start me on CAR Sched 5. Have a nice day!!:ugh:

[tnuc]

AD/ENG/4 Amdt 10 lays out the conditions that must be met to allow an engine to remain in service. The use of the term "on condition" is quite often used to describe an engine that is outside the manufactures recomended overhaul period (for exampole 2000 hr / 12 yr) when actually all engines are maintained "on condition" from the day they are installed.

[chad sexington]

I'm curious about actual experience with engines that have gone as much as 50% beyond the recommended TBO.

When overhaul time actually arrives, does it come with greater expense?
Do major components that aren't normally replaced perhaps require it?
e.g. replacing a crankshaft instead of regrinding it.

Would like to know folks opinion on whether this is a genuine cost saving or simply forestalling the inevitable.

[tnuc]

the most economical time to overhaul the engine would be at the manufactures TBO (or a little over depending on the type of operation), the further you run the engine obviously there will be more wear on the various internal components.
If a crankshaft that would have been within limits at say 2000-2200 hrs needed to be replaced because you ran the engine to 2400-2500 Hrs then that 200hrs could have easily cost you an extra $10k
The other thing to think of is at overhaul parts are subject to all types of non destructive testing (magnaflux, fluro penetrant, ultrasonic) to check for defects, cracks etc. i seriously doubt that the manufacturers invented these checks just so that they could sell more parts
Whilst an engine might be running great at 2500Hrs might have good compression, oil pressure, develop power etc does your LAME have a crystal ball to look into that will tell him that the No. 3 Conecting rod bolt has a microscopic fatigue crack that is about to grow out of controll and spoil your day ?

[Wheeler]

Syd Chrome makes an interesting point...

"They (prosecution) will not accept CASA ADs in court and will merely use the Lycoming or Continental Rec TBO as the limit for that engine..thats why a lot of LAMEs will not entertain the idea. LAMEs should be able to stand behind CASA ADs as being law and if that causes people to be injured then CASA should be held resposnible not the LAME.
SC'

There are plenty of engines in the US that are running well beyond TBO and calendar time. Some have never been touched since they were new in the 70's and 80's. They almost always have good compressions and low oil consumption and pose no real problems when they do eventually decide to overhaul them. No doubt that was the basis of the CASA condition report A/D. However, as to whether its legal. here ... well AWB 02-003 (June 06)seems to suggest that CASA are having two bob each way. They refer to CAR 42 which says something about the C of R holders responsibility to maintain the aircraft in an airworthy condition using a maintenance schedule. They go on to say that the best folks to decide on the maintenance schedule are the manufacturers and good old Sched 5, which has been used as the excuse for not working to the manufacturer's schedule for years, does not mean you don't have to do what the manufacturer recommends.

Here's one scenario I hope is totally wrong.... The problem now is if your donk or any other component is outside what the manufacturer recommends and you end up in court after a bingle caused by the failure of that component, trying to prove your aircaft has been maintained to a schedule that assures its airworthiness, in the light of that AWB and CAR 42, might be tricky even if you have complied with the CASA (all care but no responsibility) A/D's.

That AWB refers to test cases where components have not been changed in accordance with the manufacturer's recommendations and CoR holders and LAME's have been found liable. Funny thing is CASA don't seem to have publicised that AWB much, which does have major ramifications for all of the Sched 5 maintenance that is going on and has gone on for many years. - So maybe it is just a butt covering exercise that they can pull out of their back pocket when one of us poor buggers ends up in court having thought we were legal working to CASA A/D's that apparently allow on-condition maintenance and that we believed are the law???

Who'd be a LAME? (or a CoR holder for that matter!)

[Cyclone Bob]

From actual experience, an O320 in a C172P 3150hrs without any cylinder work during its life. Finally bit the bullet and sent it for overhaul/exchange when the dollar was good. Strip report concluded the engine was still sound but wear starting to appear on the camshaft. Hardly forestalling the inevitable in this case. This engine paid for itself one and a half times!

[tnuc]

CAR 41 States
Maintenance schedule and maintenance instructions
(1) The holder of the certificate of registration for a class B aircraft must
ensure that all maintenance required to be carried out on the aircraft
(including any aircraft components from time to time included in or
fitted to the aircraft) by the aircraft’s maintenance schedule is carried
out when required by that schedule.
Penalty: 50 penalty units.
(2) A person must not use a class B aircraft in an operation if there is not a
maintenance schedule for the aircraft that includes provision for the
maintenance of all aircraft components from time to time included in,
or fitted to, the aircraft.
Penalty: 50 penalty units.

This is not a new rule, You have to comply with CAR 41 even if you are using Schedule 5 for the maintenance schedule, meaning in addition to schedule 5 you should be changing and maintaining items that the manufacturer lists in the aircraft maintenance schedule, if the manufacturer says a paticular item like a vacuum pump must be changed every 500Hrs you have to follow that. I does get confusing with an engine where the manufacturers (airframe) maintenance schedule will tell you to look at the engine manufacturers recomended TBO for the engine life limit, then you have AD/ENG/4 telling you otherwise, but the manufacturers life is RECOMENDED, once you go beyond that you are on your own so to say.

[nomorecatering]

Does anyone know about the effectiveness or otherwise of these electric pre-oiling pumps that are advertised. They are switched on and pressurised the oil lines before start so that you have oil pressure the second your engine starts rather than wait for it to build up after start.

They claim to reduce wear during start up where most of the engines wear occurs. But do they work as their makers claim.

[Chimbu chuckles]

Many high $ warbirds have them...I have no direct experience of them but I can't see how they would hurt.

[LeadSled]

Nomorecatering.

For aircraft not used regularly, (say once a week) they are a great idea, the reason is self-evident ---- starting dry --- how long does it take to get oil all around the engine, not just registering on the pressure gauges. Likewise I also use an oil heater, get it nice and warm before I use the pre-oiler. If you have a low usage engine, always us a multi-grade oil with corrosion inhibitor.

I have seen several "high-cam engine" cams recently, that has less than half the lift remaining, so worn they could not be re-profiled, had to be replaced. One was about 550 hours over about 12 years, with long periods of complete inactivity.

If an engine is going to be inactive (read the manufacturers instructions) use inhibiting oil and silica gel plugs. Unfortunately in my opinion, the "approved" aircraft oils are not nearly as good as some of the modern auto oils.

In some "warbirds" (Experimental) engines in US, auto multi-grades are being used with great success, reduced consumption, reduced "bits"(carbon) in the filters, and nil internal corrosion via the boreoscope.

Tootle pip!!

Tootle pip!!

[Jabawocky]

Leaddie,

I also wonder about the issue of higher tech auto oils, and the products like aeroshell 15W-50 is a better option as you suggest.

The biggest problem with say Mobil 1 which is the leading synthetic auto oil is the use of AVGAS and the deposits in the oil. Hence the semi synthetic blends like the Aeroshell and others.

Heating and priming the system has to be worth it with infrequent use engines.

J

[Brian Abraham]

higher tech auto oils, and the products like aeroshell 15W-50 is a better option

You would need to get expert advice but my reading is. The engine type certificate will spell out the oil required and to use any other voids the airworthiness in certificated aircraft. FAA AD 80-04-03 R2 requires Lycoming LW 16702 antiwear additive to be added to the oil of Lycoming O-320-H, O-360-E, LO-360-E, TO-360-E, LTO-360-E, TIO and TIGO-541 engines. Some oil manufactures have added this additive to their oils, so you need to check if you use one of these engines.
As you suggest aviation oils will no longer be formulated to deal with lead but also have other issues such as handling heat loads (air cooled engines typically run at nearly double the temp of an water cooled auto - which has viscosity implications also), auto engines run at low power whereas aviation spend their life at a constant high power (take off and cruise settings), auto oils also typically contain zinc and phosphorus. Ash deposits produced from these metal containing additives tend to form in the combustion chamber where they can cause pre-ignition. This in turn can lead to engine failure, hence aviation oils are formulated from metal free additives. Zinc will quickly destroy the master rod bearing of a radial for example and phosphorus is literally capable of dissolving your copper bearing material.
The reverse is also true in using aviation oil in automotive applications ie its not formulated to handle the requirements. Seems like oils aint oils as the ad used to say.

[Jabawocky]

Brian,.....Oils ain't Oils Sol!

The aeroshell 15W-50 is a semi Synthetic aviation oil with the Lycoming additives. I am sure some others have a similar product, however this is the one I use for the availability of it.

I do not use it in the car, mind you get this, 12 x 946ml bottles of the aeroshell I think cost me $99, and 1 x 5L of Mobil 1 is about $65-70 I think, so something in aviation is not so bag after all!:ok:

J

[kingtoad]

The problem with pre-oilers - as I see it - is that they still don't lube the areas of the engine that are "splash lubricated" prior to starting. So - yes they're good (and better than nothing) - but not the be all and end all.

[Chimbu chuckles]

To those so enamoured with overhauling engines at TBO how do you reconcile the fact that most engine failures happen in the first 500hrs from new/overhauled and those that don't then show few problems all the way through to TBO+++...particularly if they are flown often, operated knowledgeably and maintained/monitored properly?

When I overhauled my first life IO550 5 years ago at TBO+10% it was running like a swiss watch...had I known then what I know now I would have simply just kept running it and monitored it via oil analisys, boroscope, compression testing etc...and it likely would still be running perfectly now as the previous owners had 'topped it' with all new cylinders about 500 hrs before I bought it. The only reason they needed to top it were all the compressions were low from the engine not being set up/operated properly...and quite possibly from **** OEM cylinders.

If it is running well next time it reaches TBO I won't be touching it.